Automatic telephone system



Dec. 31, 1929. J voss 1,741,549

AUTOMATId TELEPHONE SYSTEM Filed Oct. 18. 1926 Imrsn or John H. UussPatented Dec. 31, 1929 UNITED STATES PATENT OFFICE JOHN H. VOSS, OFCHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC INC., OF CHICAGO,ILLINOIS, A CORPORATION OF DELAWARE AUTOMATIC TELEPHONE SYSTEMApplication filed October 18, 1926. Serial No. 142,245.

This invention relates in general to automatic telephone systems inwhich connections are established through the medium ofsubscriber-controlled automatic switches, but is more particularlyconcerned with such automatic telephone systems that include party linesand selective ringing equipment at the automatic exchange. The object ofthe invention is the provision of a new and improved automaticparty-line selective-ringing connector switch for use in such systems.

In the past various kinds of automatic party line frequency selectingconnectors have been used for establishing connections with party linesand for selectively signalling a particular party on the line. The mostcommon of these is the type which employs a special frequency-selectingrotary switch mechanism which is operated responsive to a digit toselect a particular frequency of ringing current to be used, and todetermine the side of the line to which it is to be applied. The mainfeature of this invention is the production of a party-linefrequency-selecting connector in which the frequency-selecting rotaryswitch mechanism is eliminated, and in which relays which are responsiveto a digit dialled by the calling subscriber perform the func tion ofselecting the frequency of ringing ourrent and the line to which it isto be applied to selectively signal the desired party on a party line.

The foregoing object and the features of the invention will be describedin detail in the following specification with the aid of theaccompanying drawing, in which is shown by means of the usual schematiccircuit diagrams the new and improved party-line frequencyselectingconnector and suliicient of the apparatus associated therewith for aclear understanding of the invention.

In the drawing, the new and improved party-line frequency-selectingconnector is indicated by the-reference character C. Me-

chanically the connector C is of the well known Strowger vertical androtary type having bank contacts arranged in horizontal rows or levels.The circuits of the connector ertaining to the control of the lineselection are also well known and will be described only briefly; thosepertaining to the selection of ringing current of a particular frequencyand the application thereof to one or the other side of the line forms aparticular part of this invention and will be described in detailhereinafter.

The connector C is one of a group of connectors accessible in the banksof a group of preceding selectors, connector C being accessible by wayof the trunk line, comprising conductors 2, 8, and 4. In the banks ofthe connector C access is had to subscribers lines, one of which isshown comprising conductors 110 and 111 terminating in bank contacts101, 102, and 103, and serving substations A A inclusive. At theexchange, the subscribers lines also terminate in individual lineswitches, the line comprising conductors 110 and 111 terminating in thelineswitch RLS,

which is of the well known rotary type.

The subscribers substation A, shown in full, and the other threesubstations, only the ringers of which are shown, are of the regularautomatic type, with theirringers connected from one or the other sideof the line to ground as shown. For convenience, the exponents markingthe substations have been assigned in accordance with the final digit tobe dialled to signal each substation, as will be described in detailhereinafter.

The generators G and G are common to the exchange and supply ringingcurrent of different frequencies. The busy machine Bv is also common tothe exchange and supplies the busy tone current for giving callingsubscribers the busy tone whenever connection is established with a busyline.

With this general description of the object of the invention and theapparatus shown in the drawing in mind, a detailed description of theoperation thereof will now be given. For this purpose it will first beassumed that some subscriber wishes to converse with the subscribed atsubstation A To establish this connection, the calling subscriberremoves his receiver and dials the directory number of the subscriber atsubstation A Responsive to the dialling of the first digits, automaticswitches are successively operated, each switch operating to extend theconnection to a succeeding switch, the final switch to which theconnection is extended being a connector. It may be assumed that in thismanner the connection is extended by way of trunk conductors 2, 3 and 4-to the connector C.

When the connection is extended to con nector C, a'circuit is-closed forline relay 11 which operates and closes a circuit for release relay 12.Release relay 12 operatesand performs its usualoperations, grounding-therelease trunk 3 at armature 27, grounding the holding conductor atarmature 28, and preparing the impulsing path at armature 29. Responsiveto the dialing of the first of the last three digits of the callednumber, line relay'1-1 operates and sends a'corresponding number ofground impulses to the vertical magnet 20, series relay 13'operating inseries therewith. The operation of the vertical magnet'20 causes theswitch wipers 71, 72, and 73 to be positioned opposite the proper levelof bank contacts. At the end of this series of impulses series relay 13deenergizes and by releasing-armature '33 extends the impulsing path tothe rotary magnet 21.

Responsive to-the dialling of the next digit of the called number, linerelay 11 again operates-andsends a number cit-impulses corresponding tothe digit'diallcd to the rotary magnet 21, multiple relay 16 operatingin parallel therewith. In operating, rotary magnet 2-1 positionsthe'switc'h wipers 71, 7 2, and 73 into engagement with the bankcontacts terminating the called line, these in this case being the "bankcontacts 101, 102, and 103.

If thevline comprising conductors and 111 is busyatthis time, groundpotential will be present'on bank contact 102, causing the energizationof the two windings of two-step busy relay 15 in series over the circuitincluding wiper 7 2 and armature 44 and its workingcontact. The busyrelay 15 operates all its armaturesand applies the busy tone current tothe upper talking conductor at armature 3-8 and prepares the lockingcircuit for itself at armature 40, which is closed as soon as .relay 16,which operated in parallel with the rotary magnet, releases its armature14. The calling subscriber, hearing the busy tone, replaces hisreceiver. This initiates the release of the operated switches in thewell known manner.

It may 'be assumed, however, that the line comprising conductors 110 and111 is idle at this time. In this case relay 15 is not operated, andwhen relay 16 releases its armatures shortly after the cessation ofimpulses to the rotary magnet 21, a circuit is closed for the lowerwinding of switching relay .17, which may be-traced from ground on therelease conductor 8, resting contact and armature 39, through the lowerwinding of the relay 17, resting contact and armature 44, wiper 72, bankcontact 102, through the winding of switching relay 106 of the rotaryline switch RLS, through the winding of the rotary magnet 107 tobattery. The current flow over this circuit is insuiiicient to cause theoperation of the stepping magnet 107, but relays 106 and 17operate,relay 106 operating just sufliciently to disconnect the line conductors110 and 111 from the normal battery and ground connections,.and relay1'? operating .to perform the following circuit changes: A ring backtone circuit is prepared at armature 18 and its working contact. Alocking circuit is closed for the upper winding of relay :17 at armature19. The short circuit around resistance 62 is opened at armature 50. Atarmature 51 direct ground potential is applied to the .test contact 102and the test contacts multiply connected therewith to mark the line tosubstation A busy. At armature 52 and its working con tact the impulsingpath is extended to relay 15. At armatures 1& and 53 normally openpoints in the talking circuit are closed.

Since the subscriber at substation A is the one with which conversationis desired, the final digit to be dialled is the digit 1. Responsive-tothe dialling of'thelast digit, which in this "case is the digit 1, relay11 again momentarily releases and sends one impulse of currentovertheimpulsing path which now extends from armature 52 and the workingcontact, resting contact and armature 37, armature 42 and therestingcontact, through the lower winding of two-step relay 15 tobattery. The 'magentic at'orce produced by current in its lower windingis only sufficientto operate armature 10. By the oper ation-of armature10, a circuit is prepared for energizing the upper and lower windings ofthis relay in series, the upper winding, however, being short circuitedduring the time of the impulse. At the cessation of this impulse ofcurrent, ground potential is removed from the junction of the twowindingsof relay 15, so this relay is operated over its two windings inseries. The magnetic force produced by current in the two windingscausesthe full operation of relay 15, its useful operation at this timebeing the preparation of the ringing circuit at armature 43 and theworking contact. The ringing-circuit is finally closed at armature 16and the resting contact when relay 16, having energized in multiple withrelay 15, deenergizes shortly after the cessation of the dialling of thedigit. The ringing circuit extends from thebattery superimposedgenerator G, resting contact and armature 5'7, resting contact andarmature 4:6, armature 43 and working contact, through the upper windingof ring-cut-olf relay 14, resting contact and armature 34;, workingcontact and armature 17, resting contact and armature 58, wiper 71, bankcontact 101, conductor 110, through the ringer at substationA"to.ground, and also through the :ringer at substation A to ground. Theringer at substation A is tuned so as not to respond to the frequency ofringing current from generator G, but the ringer at substation Aresponds thereto and signals the called subscriber.

To answer the call, the subscriber at substation A removes his receiver,and in so doing closes the direct current bridge across the conductors110 and 111, thereby closing the direct current circuit for the upperwinding of the ring-cut-oft relay ll, this circuit extending frombattery superimposed generator G to conductor 110 as traced above andthen extending over the bridge at substation A, conductor 111, bankcontact 103, wiper 73, armature 61 and the resting contact, armature'53and the working contact, armature 37 and the resting contact to ground.Ringcut-off relay 14 operates over this circuit and at armatures 3A and37 completes the talking connection, closes the locking circuit foritself at armature 36, opens a point in the impulsing path at armature37, and at armature 35 opens the locking circuit of relay 15. Theconnection is now complete and conversation may take place between thecalling and called subscriber.

At the termination of the conversation, the two subscribers replacetheir receivers, initiating the release of the operated switches as willbe described hereinafter.

To further describe the operation of the connector 0, it will be assumedthat a calling subscriber wishes to engage in conversation with thesubscriber at substation A To set up this connection, the callingsubscriber again removes his receiver and dials the directory number ofthe subscriber substation A which is the same number as the number ofsubstation A except that the final digit is 2 instead of 1. It may againbe assumed that the connector C is the one taken into use forestablishing the connection. Connector C again operates responsive tothe first two of the last three digits to position its wipers 71, 7 2,and 73 in engagement with the bank contacts 101, 102, and 103,respectively, as de scribed above.

Responsive to the last digit dialed by the calling subscriber, which inthis case is the digit 2, (assuming ,he line is again found idle) linerelay 11 again intermittently deenergizes and sendstwo impulses ofcurrent, the first impulse being sent to relay 15 which relay operatesall its armatures at the cessation of the impulse and extends theimpulsing path to the two-step wiper-rever ing relay 19 by Way ofarmature 42 and the working contact, and armature 60 and the restingcontact. The second impulse of this last digit then energizes the lowerwinding of two-step relay 19. The magnetic force produced by current inthe lower winding of relay 19 is only sufficient to cause the operationof armature 59, which prepares a circuit for energizing the two windingsof relay 19 in series, the upper winding being short circuited at thistime by reason of the ground potential at the junction of the twowindings. At the cessation of the impulse, however, this groundpotential at the junction point is removed and relay 19 is energizedover its two windings in series. The magnetic pull produced by currentflow in the two windings of relay 19 in series causes the full operationofthis relay, thereby reversing the line wipers 71 and 78 as regardstheir position in the ringing circuit at armatures 58 and 61, andextending the impulsing path to two-step relay 18 at armature 60. Thislatter operation is of no utility at this time. Shortly after thecessation of the impulses of this digit, relay 16, having been energizedin parallel with relays 15 and 19, successively, deenergizes and againcloses the ringing circuit at armature 4:6. This time the ringingcircuit extends from the generator G over a path similar to that tracedabove except that it now extends by way of the working Contact andarmature 61, wiper 73, back contact 103, line conductor 111, through theringers at substations A and A to ground instead of over line conductor110 through the ringers at substations A and A The ringer at substationA is tuned so as not to respond to current from generator G. The ringerat substation A however, responds to signal the subscriber at thatsubstation. In response thereto, the subscriber at this substationremoves his receiver, thereby placing a direct current bridge across theline conductors, again causing the operation of the ring-cut-otf relay14. The return circuit for relay 14 this time includes conductor110,bank contact 101, wiper 71, armature 58 and the working contact, toground at the resting contact of armature 37, Relay 14: operates asdescribed in the previously described connection and completes a talkingconnection, whereupon the two subscribers may engage in conversation. Atthe termination of the conversation, release of the operated switch iseffected as will. be described later.

It will now be assumed that the calling subscriber wishes toconverse'with the subscriber at substation A The calling subscriberdials the directory number of the subscriber at substation A which isthe same as that of the substation A except that the last digit is 3instead of 1. It will again be assumed that the connector C is taken foruse. Connector C again operates responsive to the first two of the lastthree digits of the number to position its wipers 71, 72, and 73 on bankcontacts 101, 102, and 103, respectively and tests the line for the busyor idle condition. Assuming that the line is idle at this time, thesubscriber dials the final digit 8. Relays 15 and 19 again operatesuccessively responsive to the first and second impulses as describedabove. As stated above, relay 19, in operating in its second step,extends the impulsing path to relay 18at armature'60. Thereforeflhelower winding of relay 18 is energized by the third impulse.Theanagneticpull .producedby current in the lower winding of relay 18 isjust sufiicient to operate armature 54 which prepares a circuit forenergizing the two windings of relay 18 inscries, the upper w 1gbeing:sliort-circuited during the time o f the third impulse. At thecessation of this third impulse, ground potential is removed from thejunction point of the two windings of relay 18, thereby permitting relay18 to operate over its two windings in series causing the full operationof this relay. As a result, generator G is substituted for generator Gat armature 57 and the working contact and .the impulsing pathIisextendedto relay 13 at armature '56. Again a ringing circuit isclosed-byt'he release'of relay 16 at armature 416 shortly after thecessation of the third impulse. This ringing circuit is the same as thattraced when the ringer at substation A was operated except that ,thegenerator G has been substituted for generator G. The ringer atsubstation A is tuned so as not to respond to current from generator Gbut the ringer at substation A tuned to respond to current from thisgenerator. Thus, the subscriber at substation A is signalled. llemovingthe receiver .at substation A to answer the call againcausesthe-operation of the ring-cut-ofi relay 14- which interrupts theringing circuit and completes the talking connection in the mannerdescribed previously. At the termination of the conversation release ofthe operated switches takes place as ill be described hereinafter.

To describe how the subscriber at substation A. is signalled, it'will beassumed that a calling subscriber desires to converse with thesubscriber at substation A, and so dials his number which is the same asthat of substation A except that the final digit is 4;. It may again beassumed that the connector C is taken into use and is operatedresponsive to the first two of'the last three digits of the callednumber to position the wipers? 1, '72, and 73 on bank contacts 101, 102,and 103, respectively, and test the line. Assuming the line is idle,again relays 15, 19, and 18are respectively operated responsive to thefirst three impulses of the finaldigit which in this case is 4. Asmentioned in the previous description, relay 18, in operating fully,extends the impulsing circuit to relay 13at armature 56. Thus, thefourth impulse of the final digit traverses the impulsing path to theWorking contact and armature 5'6, winding of series relay 13, resistance62, windingof vertical magnet, to battery. The current in theimpulsing-circuit is limited by the resistance 62 .so the operation ofvertical magnet 20 is prevented. Relay 13 operates, however, and atarmature 32 opens the circuit of the two windings of wiper-reversingrelay 19. As a result, relay 19 denergizes and again reverses theconnections of wipers 711 and 73 back ;to normal as regards the upperand lower talking conductors. Now when relay 16 ideenergizesshortlyafter the cessationofimpulses, a ringing circuit is again closedover line conductor 1110 to the ringers at substations A and A this timetroni generator G in stead of generator G. The ringerat substation A istuned so as not to respond to current from generator 1G but the ringer$31113" station A is tuned to respond ,to current from this generator,and therefore the subscriber at this substation issignalled. When thereceiver at the substation is removed to answer the call, the ring-outell relay 14 is again operated and the -,talk-ing.connection iscompleted as previously described.

At the termination of the conversation the subscribers replace theirreceivers which initiates the release of the operated switches. At thereplacementot the receiver at the calling station, line relay -11denergizes and opens a circuit release relay at 12. Release relay 12deenergizes, removes the ground potential from release conductor 3 andholding-conductor 100 at armatures 27 and 28, respectively, and alsocloses theicircuit for the release magnet 22 at armature 29,, oil-normalsprings 63 havingclosed upon the first vertical'step of the switchwipers. The removal of ground from the release conductor 3 in itiatesthe release of the precedinglyoperated switches, and the removal ofground trom the holding conductor 100 opens the holding circuits-ctrelays, 1 1, 17, 18, and 19, causing the release .of these relays. Relay1.7, in re leasing armature .51, removes ground potential from bankcontact 102 thereby causing the release of relay 106.

This completes the description of the operation of this new and improvedpartyline frequency-selecting connector. What is thought newrand isdesired :to have protected by Letters Patent will be specifically statedin the appended claims.

WVhat is claimed is:

1. In a telephone system, a connector switch, party lines accessiblethereto, means for operating said switch to select a "line, a source ofsignalling current, a relay in said switch actuated responsive to oneimpulse of a series of impulses sent to said switch and deactuatedresponsive to another impulse of said series, and means controlled bysaid relay for applying said source of ringing current to either side ofthe selected line to signal either one of two parties connected to saidline depending on the number of impulses in said series.

2. In a telephone system, a connector switch, party lines accessiblethereto, ineans for operating said switch to select a line, a

plurality of sources of ringing current,-a first and a second relay insaid switch, said first relay being actuated responsive to one impulseof a series sent to said switch and deactuated responsive to anotherimpulse of said series, and said second relay being actuated responsiveto another impulse of said series, and contacts on said relays forapplying either of said sources of signalling current to either side ofthe selected line to signal a particular party on said line depending onthe state of operation of said relays as goverened by the number ofimpulses in said series.

8. In a telephone system, a connector, party lines', means for operatingsaid switch to select a line, a first and a second source of signallingcurrent, the first of said sources being normally adapted to be appliedto one side of a selected line, a first relay actuated responsive to oneimpulse of a series sent to said switch to adapt said first source to beapplied to the other side of the selected line, a second relay actuatedresponsive to another impulse of said series for substituting saidsecond source for said first source, and a third relay actuatedresponsive to a third impulse of said series for deactuating said firstrelay thereby adapting the said second source to he applied to said oneside of the selected line.

4;. In a telephone system, party lines, a two motion connector switchhaving access to said lines, means responsive to two series of impulsessent to said switch for operating said switch to select a line, saidmeans including a relay operated during the primary motion of saidswitch to cause said switch to operate in its secondary motion, a sourceof signalling current, a wiper reversing relay for controlling theapplication of said signalling current to either side of the selectedline to signal a particular party on the selected line, means forcausing said last relay to be actuated responsive to one impulse of athird series sent to said switch, and means for causing said first relayto be actuated responsive to another impulse of said third series todeactuate said last relay.

5. In a telephone system, a party line, a connector switch, meansresponsive to impulses sent to said switch for operating said switch toconnect with said line, counting relays responsive to other impulsessent to said switch for selecting a particular party on said line, andcircuit arrangements such that one of said counting relays alsofunctions as a busy test relay.

6. In a telephone system, a party line hav- I ing ringers connected toone or the other side ofthe line, a connector switch, means responsiveto impulses sent to said switch for operating said switch to connectwith said line, a plurality of sources of ringing current, and countingrelays responsive to other impulses sent to said switch for selectingone of said sources and for selecting the side of the line to which theselected source is to be applied to signal a particular party on saidline.

7. In a telephone system, party lines having ringers connected to one orthe other side of the line, a connector switch for extending connectionsto said lines, a plurality of sources of ringing current, and meansconsisting solely of relays for selecting a par-- ticular source ofringing current and the side of the line to which it is to be applied.

8. In a telephone system, a party line, a connector switch, means foroperating said switch to connect with said line, a plurality of sourcesof ringing current, and counting relays for selecting one of saidsources and for selecting the side of the line to which the selectedsource is to be applied to signal a particular party on said line, eachof said relays being responsive to an impulse sent to said switch andone of said relays being responsive to two impulses sent to said switch,the source selected and the side of the line to which it is to beapplied depending on the number of impulses sent to said switch.

9. In a telephone system, a line, a plurality of stations on said line,a connector switch, means for operating said switch to connect with saidline, and counting relays less in number than the number of stations onsaid line and responsive to impulses sent to said switch for selectingany station on said line, the particular station selected depending onthe number of impulses sent to said switch.

10. In a telephone system, a line, a plurality of subscribers stationson said line, a connector switch, means for operating said switch toconnect with said line, a plurality of sources of ringing current, andcounting relays less in number than the number of stations on said lineand responsive to impulses sent to said switch for selecting one of saidsources and a side of the line to which it is to be applied to signalany one of the subscribers on said line, the particular subscribersignalled depending on the number of impulses sent to said switch.

11. In a telephone system, a connector switch, a line, means responsiveto impulses sent to said switch for operating said switch to connectwith said line, a source of signalling current, and a busy test relay insaid switch operative responsive to the establishment of the connectionproviding the line is busy, and responsive to another impulse sent tosaid switch providing said line is idle for applying said source to saidline.

12.111 a telephone system, a line, means for establishing a connectionwith the line,

a source of signalling current, and a relay responsive to theestablishment of said con nection for giving a busy signal, providingthe line is busy, and responsive to an impulse sent to said relay forapplying said source to said line, providing the line is idle.

13. In. a telephone system, a calling line, a called line, means forestablishing a connection from said: callingline' to said called line,a. source oi signalling current, a relay automatically responsive to theestablishment of said connection for giving a busy signal, providing thecalled line is busy, and means controlled. over the calling line foroperating said relay to apply said source to said called line, providingthe called line isidle.

14. In a two motion party line connector, a changeover-relay, counting:relays for con.- trolling selective ringing, and circuit arrangementswhereby said changeover relay is used. as a counting relay in order toreduce the total number otrelays required.

15. In a twomotion party line connector, a. busy test. relay, countingrelays for controlling selective ringing, and circuit arrangementswhereby said busy test relay is used as a counting relay in order" toreduce the total number of relays. required.

16.. In a two-motion party line connector, a. changeover relay, a busy"test relay, counting relays for controlling selective ringing, anclicircuit. arrangements whereby said changeover relay and said busy testrelay are both used; as counting relays in order tore duce the totalnumber of relays required.

17.. In. a telephone system, a two motion switcln having wipers, achangeover relay, a wiper reversing relay responsive to an impulse ofcurrent sent to said switch, and means foncausing said first relay to.be actuated responsive to another impulse of current sent to said switchto deactuate: said. Wiper reversing relay.

18; In a telephonesystem, a. party line havizng ringers connected to oneor the other side of the line, a connector switch for extending aconnection tov said line, a plurality of sourcesof ringing current,counting relays responsive to impulses sent to said switch, meanscontrolled by one of said counting relays. for selecting one of saidsources, and means controlled by another of said counting relays forselecting the side: of the line to which the selected source is to beapplied to signal a particular party on said. line.

19'. Ina selective ringing device, a relay energized responsive to oneimpulse of a train, means for deenergizing said relay responsive toasubsequent impulse ofthe train, provided. the train includes enoughimpulses whereby the condition of the relay at the end of the train ofimpulses depends on the number of impulses in the train, a ringingcircuit controlled by said relay when energized, and a different ringingcircuit controlled by said relay when deenergized'.

20. In aparty line connector having two movements'to select a line, achange-over relay for controlling the shift from the first movement tothe second counting relays operated by a train of impulses separate fromthe setting impulses, one of said relays being energized responsivetoaparticular train to select a particular party, means for operating; saidchange-over relay responsive to a different train, and means fordeenergizing said energized counting relay responsive to the operationof said change-over relay to select a di'fierent party.

21. In. a two-motion switcl1,.a change-over relay, a series of countingrelays, and a, look;- ing circuit for one counting relay controlled bysaid change-over relay.

22. In combination, a series of counting relays, means for energizingsaid rel'aysone after the other responsive tosuccessive. inrpulses of atrain, another relay energized responsive to another impulse of: thetrain, and means for deenergizing'one of said: counting relaysresponsive to the energization of said other relay.

23. In combination, a plurality of count.- ing relays, said pluralityconsisting of not less than three relays, meansfor successivelyentergizing said relays-responsive to: a like plu= rality of impulses ina: train, and means for deenerg-izing one of said relays in case thenumber of impulses in the train exceeds the number of counting relays.

2 1. A counting relay arrangement as set fortlr in claim 23, in whichthe counting re lays constitute a series as regards the order in whichthey are energized and in: whiclr the relay which is deenergized is anintermediate relay of the series.

In witness wl iereof, I- hereunto subscribe my name this 14th day oiOctober, A, D2,

JOHN H-. VOSS.

